Due to their relative simplicity, reduced fluid models based on a strong guide field ordering, have proved to be valuable tools for analytical and numerical investigations of phenomena such as turbulence, magnetic reconnection and linear instabilities (see, for instance, Refs. 1-5).
In some cases, such models have been shown to possess, in their non-dissipative limit, a noncanonical Hamiltonian structure (see Ref. 6 for a review). Often associated with such structure is the possibility of casting the fluid evolution equations in a remarkably simple form which, in the two-dimensional limit, reduces to the form of advection equations for appropriate Lagrangian invariants. In this contribution I will show that this feature is part of a more general structure belonging to infinite classes of Hamiltonian reduced hybrid, drift-fluid and gyrofluid models that can be derived from gyrokinetic equations [7-9].References1. A.A. Schekochihin et al., The Astrophys. J. Suppl. Series, 182, 310 (2009).
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5. I. Keramidas Charidakos, F.L. Waelbroeck, P.J Morrison, Phys. Plasmas, 22, 112113 (2015).
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8. E. Tassi, J. Phys. A: Math. and Theor., 52, 465501 (2019).
9. E. Tassi, submitted (2023).
